From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical description of lubrication systems in various types of aircraft engines, including Vee and radial types.
| Identifier | ExFiles\Box 141\2\ scan0159 | |
| Date | 31th May 1936 guessed | |
| 113 q 5. terest to note that the piston pins are not pressure feed lubricated. (Figure 10 and Figure 11). Figure 12 illustrates a well known Vee type liquid cooled aircraft engine. Figure 13 is an anti-propeller end view of a supercharged and geared model of the same engine for which the lubrication is generally similar. The hollow supercharger shaft is the main oil supply line, (Figure 14) feeding the supercharger shaft bearings, each main bearing and from the main bearings to the connecting rod pins through passages drilled in the crankcheeks. A separate line leads to the overhead camshaft which is supplied under pressure. This and the two preceding engines are of the dry sump type and employ scavenge pumps to return oil to the storage tank. The six cylinder engine scavenges from the rear end of the camshaft housing to which oil collecting in the crankcase is drained. The Vee type engine scavenges from the front end of the oil pan to which oil from the camshaft housing is drained. Figure 15 shows a large radial air-cooled aircraft engine employed largely in air transport service. Oil is drawn from the main supply tank back of the engine by a pump mounted on the left side of the rear section cover. The pressure pump discharges oil into a built in strainer of the leaf and spacer type with the oil flow protected by a pressure relief valve by-passing the strainer in the event of clogging and controlling the pressure and flow of oil. From the end of the strainer (Figure 16) the oil flows through an annular passage and annular groove in the crankshaft extension shaft forward through a drilled hole in the rear crankcheek and thence to the center of the crankpin. All of the oil for the crank section of the engine passes through the crankpin. The oil supply for the knuckle pins and articulated rod bushings is supplied by holes drilled in the master rod bearing, registering each revolution with the discharge from the crankpin. Behind the master rod bearing a passage connects with drillings in the master rod leading to the knuckle pin holes in the master rod flange. A drilled hole in each knuckle pin indexes with each oil lead in the flange and conducts oil to the center of the knuckle pin from which it is discharged through a flat in the knuckle pin to the surface of the bushing. Oil is carried forward through the crankshaft to lubricate the cam drive gear, cam bearing and through a passage in the hollow crankshaft surrounding the breather tube which acts as a header to supply oil to the reduction gear, their bearings and the nose section. (Figure 17). The rear section is lubricated by drilled passages from the annular chamber in the crankshaft extension previously mentioned. No small part of the success of individual lubricating systems is dependent upon refinements in design intended: (a) To supply additional oil to surfaces critically loaded or at high temperature. (b) To cool the oil in the crankcase or prior to its return to the main storage tank. (c) To separate precipitants or sludge from the supply to the bearings. Some of these are worthy of mention, such as the rifle drilled connecting rod used in at least one of the engines previously mentioned. Figure 18 illustrates this device designed to carry oil under pressure to the piston pin. The head of oil in this vertical tube may also have a useful effect in lubricating the connecting rod bearing in that the inertia head on the supply in this tube will tend to supplement momentary deficiencies in the supply to the rod. | ||